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PHYSICS PHD DISSERTATION DEFENSE: Purnima Balakrishnan

Ph.D. Candidate:  Purnima Balakrishnan
Research Advisor:  Yuri Suzuki

Date: Monday, April 13, 2020
Time: 2pm
Zoom Meeting Link: https://stanford.zoom.us/j/499287340
Meeting ID: 499 287 340
Password: Email maria.frank@stanford.edu for password

Title: Electron, Oxygen, and Spin Transport in Complex Oxide Perovskites

Abstract:

The manipulation of the spin of charge carriers within solid-state materials has the potential to greatly reduce power consumption and increase computational speeds and information storage densities.  The development of these spintronic devices requires development of new materials which can be used to efficiently generate, propagate, and detect spin currents.  One promising class of materials to use are the complex oxide perovskites, which exhibit a rich variety of tunable electronic and magnetic properties.  In this presentation, I will cover two efforts to develop materials for spintronics applications.

The first part of this talk focuses on the surprising discovery that the pulsed laser deposition process used to grow homoepitaxial thin films of oxygen-deficient SrTiO3-δ can significantly change the properties of the underlying SrTiO3 substrate.  In the search for a low-dimensional metal with high mobility and high spin-orbit coupling, I find that the plume dynamics and kinetics during thin film growth cause oxygen-reduction of and conductivity in the entire substrate, at a significantly faster rate than other methods.  This has implications for thin film growth of many different materials.

The second half of this talk focuses on generation of a spin current via microwaves in a low-loss ferromagnetic metal, (La2/3Sr1/3)MnO3, and its transmission across an epitaxial interface with a non-magnetic metal, CaRuO3.  Using ferromagnetic resonance spectroscopy, I not only find evidence of efficient spin pumping across the interface, but also find that the orthorhombic CaRuO3 can affect the magnetic anisotropy in these heterostructures.  While complex oxides remain promising candidates for spintronics, the integration of different materials offers additional degrees of freedom which must be fully understood to engineer this additional functionality.

 

April 13, 2020 - 2:00pm